1. Field of the Invention
The present invention relates to an electrophoretic display and a method of driving the same, and more particularly, to an electrophoretic display with threshold voltage drift compensation functionality and a method of driving the same.
2. Description of the Prior Art
Because flat panel displays (FPDs) have advantages of thin appearance, low power consumption, and low radiation, various kinds of flat panel displays have been developed and widely applied in a variety of electronic products such as computer monitors, mobile phones, personal digital assistants (PDAs), or flat panel televisions. Among them, electrophoretic displays (EPDs), also known as electronic papers, have gained more and more attention due to further advantages of thinner feature, flexible body, and easy-to-carry property. In general, the electrophoretic display comprises a gate driving circuit, a data driving circuit and plural pixels. The gate driving circuit is employed to provide a plurality of gate signals. The data driving circuit is employed to provide a plurality of data signals. Each of the pixels includes a data switch, an electrophoretic medium and plural charged particles suspended in the electrophoretic medium. The color of the charged particles is different from that of the electrophoretic medium. The data switch provides a control of writing a corresponding data signal with the aid of a corresponding gate signal, for changing the voltage difference across opposite sides of the electrophoretic medium. And the voltage difference across opposite sides of the electrophoretic medium can be employed to create an electric field for adjusting the position of the charged particles in the electrophoretic medium. Accordingly, the grey level of each pixel can be set according to the color contrast between the charged particles and the electrophoretic medium in conjunction with the suspension depth of the charged particles.
In the operation of the electrophoretic display, each frame time includes a writing period and a retaining period. During the writing period, the charged particles of each pixel are moved to a proper position for setting a desirable grey level. During the retaining period, the charged particles of the pixels are retained to stay in the positions respectively adjusted during the writing period so as to display an image. However, each gate signal holds a low reference voltage for most of operating time, i.e. each gate signal holds a high reference voltage only for small part of operating time. For that reason, the voltage stress of the data switch is mainly caused by the low reference voltage, which is likely to incur an occurrence of threshold voltage drift and degrades the reliability and life-time of the electrophoretic display.